OneLogin_Saml2_Settings::validateMetadata PHP Method

    public function validateMetadata($xml)
    {
        assert('is_string($xml)');
        $errors = array();
        $res = OneLogin_Saml2_Utils::validateXML($xml, 'saml-schema-metadata-2.0.xsd', $this->_debug);
        if (!$res instanceof DOMDocument) {
            $errors[] = $res;
        } else {
            $dom = $res;
            $element = $dom->documentElement;
            if ($element->tagName !== 'md:EntityDescriptor') {
                $errors[] = 'noEntityDescriptor_xml';
            } else {
                $validUntil = $cacheDuration = $expireTime = null;
                if ($element->hasAttribute('validUntil')) {
                    $validUntil = OneLogin_Saml2_Utils::parseSAML2Time($element->getAttribute('validUntil'));
                }
                if ($element->hasAttribute('cacheDuration')) {
                    $cacheDuration = $element->getAttribute('cacheDuration');
                }
                $expireTime = OneLogin_Saml2_Utils::getExpireTime($cacheDuration, $validUntil);
                if (isset($expireTime) && time() > $expireTime) {
                    $errors[] = 'expired_xml';
                }
            }
        }
        // TODO: Support Metadata Sign Validation
        return $errors;
    }

 /**
  * Returns the metadata of this Service Provider in xml.
  * @return string Metadata in xml
  * @throws \Exception
  * @throws \OneLogin_Saml2_Error
  */
 public function getMetadata()
 {
     $oneLoginSetting = new \OneLogin_Saml2_Settings($this->config, true);
     $metadata = $oneLoginSetting->getSPMetadata();
     $errors = $oneLoginSetting->validateMetadata($metadata);
     if (!empty($errors)) {
         throw new \Exception('Invalid Metadata Service Provider');
     }
     return $metadata;
 }